Drill jig apparatus

ABSTRACT

An apparatus for holding a workpiece, e.g., a rod or conduit, in working proximity with a drill press or the like so that a plurality of precision aligned transverse holes may be drilled along the length of the workpiece with further assurance that the center line of the holes are coincident with a single longitudinal radial plane of the workpiece. The apparatus includes a substantially identical pair of alignment blocks having apertures therein for receiving the workpiece, i.e., one being a &#39;&#39;&#39;&#39;reference&#39;&#39;&#39;&#39; block and the other being a &#39;&#39;&#39;&#39;slidably adjustable&#39;&#39;&#39;&#39; block. The reference block includes structure for engaging and rigidly holding the workpiece. The adjustable block includes a plurality of accurately positioned drill guides of different sizes and is adapted to be positioned along the length of the workpiece at predetermined locations thereon for drilling the plurality of holes therein, i.e., regardless of the location at which the adjustable block is placed along the workpiece the centerline of the appropriate drill guide will consistently be accurately positioned for drilling the above-described precision aligned holes, providing the reference and adjustable blocks are resting upon a planar surface.

United States Patent [191 Smith DRILL JIG APPARATUS [75] Inventor: JamesP. Smith, Memphis, Tenn.

[73] Assignee: Robert O. Manspeaker, Memphis,

Tenn, a part interest 22 Filed: July 19,1971

21 Appl.No.: 163,903

FOREIGN PATENTS OR APPLICATIONS 590,005 7/1947 Great Britain 408/97661,420 11/1951 Great Britain 408/72 Primary Examiner-Gil WeidenfeldAttorney-John R. Walker, 111

- [451 July 3,1973

57 i ABSTRACT An apparatus for holding a workpiece, e.g., a rod orconduit, in working proximity with a drill press or the like so that aplurality of precision aligned transverse holes may be drilled along thelength of the workpiece with further assurance that the center line ofthe holes are coincident with a single longitudinal radial plane of theworkpiece. The apparatus includes a substantially identical pair ofalignment blocks having apertures therein for receiving the workpiece,i.e., one being a reference block and the other being a slidablyadjustable block. The reference block includes structure for engagingand rigidly holding the workpiece. The adjustable block includes aplurality of accurately posi tioned drill guides of different sizes andis adapted to be positioned along the length of the workpiece atpredetermined locations thereon for drilling the plurality of holestherein, i.e., regardless of the location at which the adjustable blockis placed along the workpiece the centerline of the appropriate drillguide will consistently be accurately positioned for drilling theabovedescribed precision aligned holes, providing the reference andadjustable blocks are resting upon a planar surface.

7 2 Claims, 6 Drawing Figures INVENTOR. JAMES E SMITH DRILL JIGAPPARATUS BACKGROUND or THEIINVENTION 1. Field of the Invention Thisinvention relates to work holding devices.

2. Description of the Prior Art The usual practice in drilling holes ina workpiece, e.g., an elongated conduit or rod, is to rest the workpiecein a V-block which may include a horseshoe clamp for immobilizing theworkpiece in the V-block. In the event a plurality of holes are desiredin a straight line, i.e., traverse holes having their centerlines in asingle longitudinal radial plane, along the length of the workpiece, atypical straight edge is employed to scribe a longitudinal straight linealong the length of the workpiece. Transverse scribe lines arepositioned along the length of the longitudinal scribed line atpredetermined locations peculiar to the ultimate use of the workpiece. Acenter punch is used to impinge the workpiece at the plurality ofintersections providing for a twist drill starting depression in theworkpiece.

In other words, the holes are only as accurately placed as is theability of the workman to properly sight the longitudinal scribed lineprecisely at the top dead center of the workpiece, the transversescribed lines at exactly the proper spaced apart distance, and properlyposition the center punch when impinging the starting depression for thetwist drill. It should be quite apparent to those skilled in the artthat the above criteria is virtually impossible to achieve. However,assuming that the above criteria was precisely accomplished, themolecular structure of metal is such that twist drills tend to walk in adirection toward softer metal even when small pilot holes are firstdrilled therein. Accordingly, the holes usually are longitudinallytangential, i.e., parallel to a plurality of tangents to the surface,rather than longitudinally radial, i.e., along one of the radii, whetherthe workpiece be drilled with a drill press or with a portable freehanddrilling device.

The environment for the majority of the workpieces is such that theabove-described technique is accept able. However, certain environmentsdo not allow for such wide tolerances of accuracy, e.g., high pressuregas burners having an error greater than 1 [10,000 of an inch is aproblem. The usual practice in manufacturing these burners is to gangdrill the gas iron blank workpiece with holes which receive bronzenozzles or the like which may be subsequently aligned so as to comewithin the established tolerance. This procedure is costly in materialand labor. Additionally, an elaborate machine is required to precisionalign the jets, further adding to the cost in the production of highpressure gas burners. v

A search was conducted which revealed the following two patents: TheHurd U.S. Pat. No. 190,042 and the Armstrong U.S. Pat. No. 1,109,952.The Hurd U.S. Pat. No. 190,042 pertains to a work holding device fordrilling machines and the following quotes from the specificationthereof are cited:

My invention therefore consists, first, of a rotary adjustabledrill-gig, which constitutes the blank-holder and drill-guide; second,in an index or angular guide to determine the exact angular positiondesired; third, in removable guide-bushings, which may be adapted to thevarious sizes of boring-tools employed.

Absolute truth of operation is not attainable; but it is possible towork within a margin of error practically inappreciable, and hence, forreasons hereinbefore stated, it is required that the boring shall notproceed from one side beyond center. The work must then be reversed andthe boring recommenced on the opposite side.

The Armstrong U.S. Pat. No. 1,109,952 pertains to a saw guide for gaspipes. The structure of the U.S. Pat. No. 1,109,952 invention consistsof a block which is provided with a hole for receiving a plurality ofbushings which individually are compatible with a particular size pipe.The block is additionally provided with a cross slot in the front facethereof, and obviously is arranged at a right angle to the face andlikewise to the hole which receives the pipe. This slot serves as therunway for a saw and intersects the hole at a depth sufficient to permitthe saw to run through the pipe and allow it to be entirely cut off.Thus, the block may be positioned at predetermined locations along thepipe so that the pipe may be severed to a desirable length. Anadjustable stop is also provided to form a flat bearing surface which inpractice is seated against the wall or ceiling of a building from whichthe pipe to be cut projects.

Obviously, neither of the above patents solves the problem of providinga workpiece holding means for drilling a plurality of precision alignedtransverse holes along the length of the workpiece with each of thecenterlines of the holes being in a single longitudinal radial planethereof.

SUMMARY OF THE INVENTION The present invention is directed towardsovercoming the disadvantages and problems associated with precisiondrilling a plurality of transverse holes along the length of aworkpiece, i.e., each of the centerlines of the holes being in a singlelongitudinal radial plane of the workpiece.

The structure of the present invention includes a referencemulti-lateral blocklike member and at least one similar slidablyadjustable multi-lateral blocklike member. The reference and adjustableblocklike members are intended to be supported by a planar work surfacetypically associated with a boring means, e.g., a drill press or thelike. Each of the blocklike members are provided with an aperture forloosely receiving the workpiece, e.g., when the multi-lateral blocklikemembers have four sides thereto, the aperture also preferably has foursides. The aperture is diagonally disposed with respect to the profileof the blocklike members, i.e., each apex of the angles formed by theaperture is adjacent one side of the blocklike member so that when theworkpiece extends through the blocklike members, it is suitably alignedby engagement of circumferential portions thereof with adjacent sides ofthe aperture, i.e., the blocklike members suitably'resting upon theplanar surface.

The reference blocklike member includes means for engaging and rigidlyholding the workpiece. The adjustable blocklike member includes at leastone twist drill guide means having the centerline thereof extendingperpendicular to the centerline of the aperture which receives theworkpiece. The opening in the drill guide means intersects the aperturefor guiding a twist drill directly in line with the longitudinal radialplane of the workpiece.

In other words, the aperture in the adjustable blocklike member ispositioned therein so that the bisecting plane of the angle defined bytwo adjacent straight sides thereof is coincident with the centerline ofthe drill guide means. Additionally, the planes of the adjacent straightsides defining the aperture in the adjustable blocklike member arecoincident with the planes of the straight sides defining the apertureof the reference blocklike member, i.e., when the reference andadjustable blocklike members are resting upon the planar work surface.

The adjustable blocklike member is adapted to be positioned along thelength of the workpiece at predetermined locations thereon for drillingany number of transverse holes therein, i.e., the holes being in asingle longitudinal radial plane of the workpiece.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front elevational view ofone of the blocklike members of the present invention having a portionthereof broken away, showing a cross section of a workpiece or conduitin phantom.

FIG. 2 is a sectional view taken as on the line IIII of FIG. 1.

FIG. 3 is a side elevational view of a pair of the blocklike members ofthe present invention shown in a preferred environment with theworkpiece extending through both members, also showing an alternatereference blocklike member in phantom and the members and workpiecebeing adjacent a drill press having a planar work surface and a twistdrill.

FIG. 4 is a view similar to FIg. 3 showing one of the block membersconstituting a reference blocklike member by having a drift pin insertedtherein for engaging and rigidly holding the workpiece thereto.

FIG. 5 is a front elevational view of the alternate reference blocklikemember.

FIG. 6 is a side elevational view of the alternate reference blocklikemember, having a portion thereof broken away.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring first to FIGS. 3 and 4of the drawings, wherein it may be seen that the apparatus 11 of thepresent invention is directed toward holding an elongated cylindricalworkpiece 13, e.g., a rod or conduit, adjacent a drill press 15 or thelike having a planar work surface S and a twist drill 17 for drilling aplurality of precision aligned transverse holes 19 along the length ofthe workpiece 13 with each of the centerlines of the holes 19 being in asingle longitudinal radial plane of the workpiece 13.

The apparatus 11 generally comprises a reference multi-lateral blocklikemember 21 and at least one slidably adjustable multi-lateral blocklikemember 23. Each of the blocklike members 21, 23 are provided with anaperture 25 (FIG. 1) for loosely receiving the workpiece l3, i.e., eachof the apertures 25 being defined in part by at least two adjacentstraight sides 27, 29 disposed at an angle A of less than 180 forengagement by circumferential portions of the workpiece 13. It should beunderstood that the blocklike members2l, 23, as herein illustrated anddisclosed include front and back sides 31, 33 and four substantiallyidentical side portions 35a, 35b, 35c, and 35d. Also, it should bepointed out that the line of intersection 30 of the sides 27, 29 isparallel with side 35a. Additionally, the aperture 25 is defined by thetwo adjacent straight sides 27,

29 and two additional straight sides 37, 39, thus substantially defininga square having the angle A, an angle A, an angle A", and an angle A'.However, the blocklike members 21, 23, or more specifically, the frontand back sides 31, 33 may be shaped to define a triangle, a pentagon, ahexagon, and/or other polygon figures with the respective apertures 25therein having corresponding shapes thereto without departing from thespirit and scope of the present invention. The lines of intersection ofthe sides of the apertures forming the angles for engagement bycircumferential portions of the workpiece 13 are parallel with theadjacent side portion of the blocklike members 21, 23 which rests uponsurface S.

The reference blocklike member 21 includes means for engaging andrigidly holding the workpiece 13 thereto, i.e., including structure yetto be disclosed. The adjustable blocklike member 23 includes at leastone twist drill guide 41 having the centerline thereof extendingperpendicular to the centerline of the aperture 25, i.e., the drillguide 41 having an opening therein which intersects the aperture 25. i

The aperture in the adjustable blocklike member 23 is positioned thereinso that the bisecting plane of the angle A defined by the straight sides27, 29 thereof is coincident with the centerline of the drill guide 41.Further, the planes of the straight sides 27, 29 respectively of theadjustable blocklike member 23 are coincident with the planes of thestraight sides 27, 29 of the aperture 25 in the reference blocklikemember 21, i.e., when the reference and adjustable blocklike members 21,23 are resting upon the work surface S. The adjustable blocklike member23 is therefore adapted to be positioned along the length of theworkpiece 13 at infinite predetermined locations thereon for drillingany number of previously described holes 19 therein.

The means alluded to above for engaging and rigidly holding theworkpiece 13 to the reference blocklike member 21 includes a drift pin43 (FIG. 4) and the coacting twist drill guide 41. More specifically,the location along the length of the workpiece 13 is determined for thefirst hole 19 and the reference blocklike member 21 is positionedthereon so that the drill guide 41 is centered over the location for thefirst hole 19. The drill press 15 is then used in a typical manner toinsert the twist drill 17 through the opening in the drill guide 41(FIG. 3) to drill the first hole 19. It should be understood that thetwist drill 17 may be allowed to extend on through the workpiece 13 sothat opposite walls thereof are drilled or the twist drill 17 may bepermitted to penetrate only one wall of the workpiece 13, i.e.,depending upon the intended use or specifications for the workpiece 13.

The drift pin 43 is then removably received in the drill guide 41 andthe first hole 19 in the workpiece 13 as best illustrated in FIG. 4 ofthe drawings. It should be appreciated by those skilled in the art thatthe drill guide 41 is positioned in the reference blocklike member 21 sothat the bisecting plane of the angle A defining the aperture 25 thereinrespectively is coincident with the centerlines of the drill guide 41 ofboth the ref erence and adjustable blocklike members 21, 23. In otherwords, regardless of the location at which the adjustable blocklikemember 23 is placed along the workpiece 13, the centerline of its drillguide 41 will consistently be accurately positioned to facilitatedrilling any number of transverse holes 19 having their centerlines in asingle longitudinal radial plane of the workpiece 13, i.e., provided thereference and adjustable blocklike members 21, 23 are resting on thework surfaces S or any other planar surface.

In order that the device 11 is readily adaptable to drill holes ofdifferent sizes in the workpiece 13, the reference and adjustableblocklike members 21, 23 preferably include a plurality of differentsize drill guides 41, e.g., the four-sided members 21, 23 as illustratedwould include the aforementioned drill guide 41, and three additionaldrill guides 41, 41", and 41". It should be understood that when themembers 21, 23 have hexagonal shapes, additional surfaces are providedfor accommodating additional drill guide means, etc., for otherpolygonally shaped members 21, 23.

In this regard, regardless of the shape of the blocklike members 21, 23,i.e., or the number of different size drill guides 41 therein, each ofthe aperture 25 is so shaped as to define a plurality of angles. Morespecifically, the aperture 25 is positioned in the adjustable blocklikemember 23 so that the bisecting plane of any one of the above mentionedangles is coincident with the centerline of at least one of thedifferent size drill guides 41. For example, the bisecting plane of theangle A is coincident with the centerline of the drill guide 41', thebisecting plane of the angle A" is coincident with the centerline of thedrill guide 41", and the bisecting plane of the angle A' is coincidentwith the centerline of the drill guide 41", etc., for other polygonallyshaped members 21, 23.

Accordingly, the aperture 25 for the reference blocklike member 41 isconstructed and so positioned that the bisecting plane of any one of theplurality of angles thereof is coincident with the centerline of atleast one of the different size drill guides of both the reference andadjustable blocklike members 21, 23. In other words, the constructioncharacteristics of the reference blocklike member 21 preferably aresubstantially identical with the construction characteristics of theadjustable blocklike member 23, as above disclosed.

From the above disclosure, it should now be apparent to those skilled inthe art that when the reference blocklike member 21 has square front andback sides 31, 33, the adjustable blocklike member 23 preferably hassubstantially identical square front and back sides 31, 33, etc., forother polygonally shaped front and back sides 31, 33.

Accordingly, the workpiece 13 is supported by at least one referenceblocklike member 21 and at least one substantially identical adjustableblocklike member 23, i.e., corresponding circumferential portionsthereof engaging corresponding surfaces of substantially identicalapertures 25. It should be understood that the spaced apart distance ofthe blocklike members 21, 23 is limited, i.e., the distance being avariable depending upon the rigidity of the workpiece 13. In otherwords, an exceptionally long workpiece l3, e.g., 18 or ft., would have atendency to bend when supported at only two points. In this event,additional adjustable blocklike members preferably are positioned atrandom intervals along the length of the workpiece 13 to assure that thelongitudinal axis of the workpiece 13 remains parallel with the planarsurface S.

From FIG. 4 of the drawings, it may be seen that the workpiece 13 maybeprovided with a plurality of different size transverse holes 19 witheach of the centerlines thereof being in a single longitudinal radialplane of the workpiece 13. In other words, in the event no more thanfour different size transverse holes 19 are desired, the blocklikemembers 21, 23 preferably have a shape substantially as depicted in thedrawings and as above disclosed. The desired size holes 19 is selectedby placing the appropriate side thereof upon the surface S, e.g., theside 35b contiguously engaging the surface S presents the drill guide 41to the drill press and twist drill 15, 17, etc., for the remaining sides35c, 35d and drill guides 41", 41". In the event five different sizeholes are desired in the workpiece 13, the reference and adjustableblocklike members 21, 23 preferably have the front and back sidesthereof and the apertures therein pentagonally shaped and preciselypositioned as previously disclosed, etc., for additional numbers ofdifferent size holes 19.

However, it should be understood that any number of reference and/oradjustable blocklike members 21, 23 may be provided to cover thespectrum of different size holes, i.e., two reference and/or adjustableblocklike members 21, 23 having only four different drill guides eachwould include a variety of eight different size drill guides and threewould include a variety of twelve drill guides, ad infinitum.

In this regard, it should be understood that the drill guides 41 -41constitute a well known bushing of hardened steel or the like which arepress-fitted into suitable apertures 45. Accordingly, the individualdrill guides 41 may be removed from their apertures 45 and other sizedrill guides 41 installed therein.

It should be understood that while only only one drift pin 43 isillustrated, a variety of different size drift pins 43 are included inthe present invention, i.e., a separate size drift pin for each sizedrill guide 41.

In the event a hole is desired in the workpiece 13 radially displaced180 from the holes 19 as depicted in FIG. 4, the reference blocklikemember 21 may be rotated about the centerline of the aperture 25 so thatthe side 35c thereof contiguously engages the surface S. It should beunderstood that the surface S is provided with a socket for receivingthe knurled protruding portion of the drift pin 43. Subsequentlythereto, the adjustable blocklike member 23 may be positioned along thelength of the workpiece 13 so that any number of holes may be drilledalong the length thereof radially disposed 180 thereon from the holehaving the drift pin 43 extending therein.

Referring now to FIGS. 3, 5 and 6 of the drawings, wherein it may beseen that an alternate embodiment is included with the drill jigapparatus 1 l of the present invention, which pertains to the means. forengaging and rigidly holding the workpiece to the reference blocklikemember. Accordingly, the apparatus 11 includes an alternate referenceblocklike member 121. The reference blocklike member 121 is providedwith a bore 145 which is directed towards and intersects an aperture 125therein, i.e., the bore intersecting the aperture 125 adjacent a pointopposite the apex of an angle A i.e., the angle A, corresponds to theangle A defined by the straight sides 27, 29 of the aperture 25 in thereference blocklike member 21, as fully disclosed in the principalembodiment above. In other words, the angle A, is defined by a pair ofadjacent straight sides 127, 129 of the aperture 125.

The alternate reference blocklike member 121 includes a set screw 151which is threadedly received in the bore 145 and may be manually turnedinwardly into the aperture 125 so that the innermost end thereoffrictionally engages the workpiece 13, i.e., rigidly holding theworkpiece 13 to the alternate reference blocklike member 121.Accordingly, the adjustable blocklike member 23 as above disclosed inthe principal embodiment may be used in the identical fashion inconjunction with the reference blocklike member 121, i.e., positionedalong the length of the workpiece 13 at predetermined locations thereonfor drilling the precision aligned transverse holes 19 having theircenterlines in a single longitudinal radial plane of the workpiece 13.

It should be understood that the planes of the straight side 127, 129respectively are coincident with the planes of the straight sides 27,29, i.e., when the reference blocklike member 121 and the adjustableblocklike member 23 are resting upon the work surface S. Accordingly,the reference blocklike member 121 preferably is shaped substantiallyidentical to the adjustable blocklike member 23, i.e., if the adjustableblocklike member 23 has five sides as does the aperture 25 therein, thereference blocklike member 121 would likewise have five sides as wouldthe aperture 125 therein, etc., for other polygonally shaped members 23,121.

Although the invention has been described and illustrated with respectto preferred embodiments thereof, it is not to be so limited sincechanges and modifications may be made therein which are within the fullintended scope of the present invention.

I claim:

1. An apparatus for holding an elongated cylindrical workpiece adjacentboring means having a planar work surface and a twist drill for drillinga plurality of precision aligned transverse holes along the length ofsaid workpiece with each of the center lines of the holes being in asingle longitudinal radial plane of the workpiece, said apparatuscomprising a reference multilateral blocklike member and at least oneslidably adjustable multilateral blocklike member, each of saidblocklike members being provided with an aperture for loosely receivingthe workpiece, each of said apertures being defined in part by at leasttwo adjacent straight sides disposed at an angle of less than 180 forengagement by circumferential portions of the workpiece to be drilled,said reference blocklike member including means for engaging and rigidlyholding the workpiece thereto, said adjustable blocklike memberincluding at least one twist drill guide means having the center linethereof extending perpendicular to the center line of said aperture,said drill guide means having an opening therein which intersects saidaperture, said aperture in said adjustable blocklike member beingpositioned therein so that the bisecting plane of said angle defined bythe said two straight sides thereof is coincident with the center lineof said drill guide means and the planes of said straight sides thereofrespectively being coincident with the planes of said straight lines ofsaid aperture in said reference blocklike member when said reference andadjustable blocklike members are resting upon the work surface, and saidadjustable blocklike member being adapted to be positioned along thelength of the workpiece at predetermined locations thereon for drillingsaid plurality of holes therein, said means for engaging and rigidlyholding the workpiece to said reference blocklike member including driftpin means and coacting twist drill guide means, said drift pin meansbeing removably received in said drill guide means for reception in thefirst of said plurality of holes being drilled in the workpiece and saiddrill guide means being positioned in said reference blocklike member sothat the bisecting plane of said angle partially defining said aperturetherein respectively is coincident with the center lines of said drillguide means of said reference and said adjustable blocklike members,said adjustable blocklike member including a plurality of different sizedrill guide means and said aperture therein is so shaped as to define aplurality of angles, said aperture being positioned in said adjustableblocklike member so that the bisecting plane of any one of saidplurality of angles is coincident with the center line of at least oneof said different size drill guide means.

2. The apparatus of claim 1 in which said reference blocklike memberincludes a plurality of different size drill guide means and saidaperture therein is so shaped as to define a plurality of angles, saidaperture being positioned in said reference blocklike member so that thebisecting plane of any one of said plurality of angles is coincidentwith the center line of at least one of said different size drill guidemeans of said reference and said adjustable blocklike members.

- l i i l

1. An apparatus for holding an elongated cylindrical workpiece adjacentboring means having a planar work surface and a twist drill for drillinga plurality of precision aligned transverse holes along the length ofsaid workpiece with each of the center lines of the holes being in asingle longitudinal radial plane of the workpiece, said apparatuscomprising a reference multilateral blocklike member and at least oneslidably adjustable multilateral blocklike member, each of saidblocklike members being provided with an aperture for loosely receivingthe workpiece, each of said apertures being defined in part by at leasttwo adjacent straight sides disposed at an angle of less than 180* forengagement by circumferential portions of the workpiece to be drilled,said reference blocklike member including means for engaging and rigidlyholding the workpiece thereto, said adjustable blocklike memberincluding at least one twist drill guide means having the center linethereof extending perpendicular to the center line of said aperture,said drill guide means having an opening therein which intersects saidaperture, said aperture in said adjustable blocklike member beingpositioned therein so that the bisecting plane of said angle defined bythe said two straight sides thereof is coincident with the center lineof said drill guide means and the planes of said straight sides thereofrespectively being coincident with the planes of said straight sides ofsaid aperture in said reference blocklike member when said reference andadjustable blocklike members are resting upon the work surface, and saidadjustable blocklike member being adapted to be positioned along thelength of the workpiece at predetermined locations thereon for drillingsaid plurality of holes therein, said means for engaging and rigidlyholding the workpiece to said reference blocklike member including driftpin means and coacting twist drill guide means, said drift pin meansbeing removably received in said drill guide means for reception in thefirst of said plurality of holes being drilled in the workpiece, andsaid drill guide means being positioned in said reference blocklikemember so that the bisecting plane of said angle partially defining saidaperture therein respectively is coincident with the center lines ofsaid drill guide means of said reference and said adjustable blocklikemembers, said adjustable blocklike member including a plurality ofdifferent size drill guide means and said aperture therein is so shapedas to define a plurality of angles, said aperture being positioned insaid adjustable blocklike member so that the bisecting plane of any oneof said plurality of angles is coincident with the center line of atleast one of said different size drill guide means.
 2. The apparatus ofclaim 1 in which said reference blocklike member includes a plurality ofdifferent size drill guide means and said aperture therein is so shapedas to define a plurality of angles, said aperture being positioned insaid reference blocklike member so that the bisecting plane of any oneof said plurality of angles is coincident with the center line of atleast one of said different size drill guide means of said reference andsaid adjustable blocklike members.